The invention disclosed herein is generally related to voltage converters, particularly battery-powered dc-dc voltage converters of the type commonly used to charge capacitance-based electrical storage devices. More specifically, the present invention is related to battery-powered voltage converters for charging electronic camera flash lamps.
Commercially available electronic camera flash lamps are typically driven by capacitance-based electrical storage devices which must be recharged after each flash. Such storage devices are typically recharged by means of a portable, battery-powered dc-dc voltage converter which is either contained separately or included integrally in the flash lamp unit. The time required for recharging the flash lamp between flashes is limited primarily by the power output of the voltage converter. Typical integrally contained voltage converters powered by commonly available low voltage batteries require 10 to 20 seconds to recharge a typical flash unit, a time period which is unacceptably long in many professional photographic applications. More expensive professional quality flash units utilize separately contained voltage converters which have a higher power output, but which are more complex and bulky. Other commercially available charging devices require high voltage batteries that are often not readily available.
Previously available voltage converters used in connection with camera flash lamps are also characterized by the emission of an audible, high pitched acoustic tone during the recharging period. This tone results from saturation of the power transformer typically present in the converter circuit, and is undesirable in certain professional applications, for example during press conferences.
Accordingly, it is the object and purpose of the present invention to provide a high capacity dc-dc voltage converter. More specifically, it is the object of this invention to provide a voltage converter suitable for use in charging rechargeable capacitor-based devices of the type commonly used to power electronic camera flash lamps.
It is also an object of the present invention to provide such a voltage converter adapted for use as a portable, compact power supply for recharging a camera flash unit in the field.
It is another object of the present invention to provide a high capacity voltage converter suitable for charging electronic camera flash units, and which utilizes relatively inexpensive and commonly available low voltage rechargeable batteries.
It is yet another and more specific object of the present invention to provide a battery-powered charging device for recharging electronic camera flash lamps, which recharges such lamps quickly and without emission of audible sound.